VI. Degradation of Herbicide Antidotes in Plants

The concept of using herbicide antidotes offers a potential alternative for

increasing the selectivity of currently available herbicides. A desirable herbicide

antidote is a chemical agent that selectively protects crops from herbicide injury

without protecting weeds. This selectivity is the result of either a very specific

crop-herbicide-antidote interaction or a selective treatment such as the dressing

of crop seeds with the antidote. Herbicide antidotes are developed primarily

through random screening techniques that involve most combinations of important herbicides, major crops, and candidate antidotes. Chemicals that are currently used as herbicide antidotes include NA, R-25788, CGA-43089,

The recent rise of the soybean as a major American crop is an example of the

value of research on new crops. Although it was introduced into the United

States in 1850, its production remained relatively minor until about 1960. It was

not until several developments occurred, such as characterization of the oil,

utilization of the oil and meal, and the development of adapted varieties and

optimum cultural practices, that the soybean reached its current level of

production.

In the mid 1970s, concern and support for research on potential new crops in

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LEMOYNE HOGAN AND WILLIAM P. BEMIS

the United States began to be expressed. In a report prepared for the National

Science Foundation (NSF) (Theisen ef al., 1978), the following four basic concerns for new crops research were listed: (1) the genetic pool of agricultural crops

may be vulnerable unless enriched and diversified with new genetic material; (2)

present crops are either very demanding environmentally or narrowly adapted

ecologically; (3) present crops require very high energy inputs in the fom of

fuel, fertilizers, pesticides, processing, and irrigation; and (4) the lack of production alternatives in diversified markets exposes producers unduly to price instabilities that are often induced by demand factors external to the U.S.

economy.

Other papers such as “Food and Agriculture” (Wortman, 1976) considered

the problem of feeding the world population. Harlan (1976) points out that as

agriculture evolved it changed from being highly diversified, involving thousands of species of plants of which relatively few were ever domesticated, into an

agriculture so highly specialized that most of the world population is absolutely

dependent on a handful of species. Harlan lists 30 crop species having an annual

world production of 10 million metric tons or greater. These 30 crop species have

a total yield of 2360 million metric tons and the top four crop species (i.e.,

wheat, rice, maize, and potato) account for 1280 metric tons or 54% of the total.

The failure or partial failure of any one of these species could mean automatic

starvation for millions of people. In the early 1800s Ireland developed a nearmonoculture agriculture based on the potato. Total crop failure in 1845and 1846

because of a fungal disease resulted in at least 1 million persons dying of

starvation as a direct result of the 2-year famine (Salaman, 1949).

There is, however, good reason that a few major crop species dominate world

agriculture. These crops are profitable to produce on a very large scale and are

well adapted to mechanization. The grain crops are not particularly perishable

and can be stored and transported with relative ease. Each species is particularly

adapted to large growing areas where they produce excellent yields. For example, the “corn belt” of the United States is particularly well adapted to producing corn (maize) (Loomis, 1976);the region has large expanses of relatively level

land and the soil is fertile and well drained. The growing season includes at least

120 days when the temperature is above 10°C, and ample rainfall is normally

well distributed over the growing season. Loomis (1976) states that in the western plains of the UNted States the supply of moisture is inadequate for corn,

which is therefore grown only where irrigation is possible. The wheat plant,

which dominates the semiarid croplands of the world, fills the need in these area

for a cultivated crop with a lower demand for water and a greater tolerance for

drought. Rice, a grain crop adapted to growing in fields flooded by water and

requiring a long growing season to mature, is the staple grain of much of the

world’s tropical agriculture.

These and other major staple world crops are grown in the most desirable